Helios-rc

Coating Measurement of Solar Cells

Total Reflectance, Color and Layer Thickness of Coated and Uncoated Silicon Solar Wafers

The surface texturing of crystalline solar cells plays an important role to achieve high solar cell efficiencies. The texturing reduces reflectivity losses significantly and has a strong impact on the passivation of the cell. In addition to the texturing process step itself, the quality of the silicon material and the wafer sawing process have impact on the texture. Therefore, it is essential to gain detailed knowledge of the texturing. This knowledge and process control can be achieved by precise measurement of the total reflectance of the textured cells. Our Helios-rc is the perfect tool to measure, analyze and optimize the widely used chemical texturing processes. It measures the total reflectance of bare and coated solar wafers, as well as the color and layer thickness of coated solar wafers.

Measurement of the Total Spectral Reflectance

Measurement of the total spectral reflectance is a good and accepted method for maintaining a stable texturing process. The texturing affects the average level of the Reflectance and also the amount of spread/variation of the Reflectance over the

wafer. Both, the average Reflectance level and the variation of the Reflectance over the wafer, are important and need to be controlled.

Functions of Helios-rc

Helios-rc systems are designed for precise monitoring and control of texturing and etching processes on solar wafers. These systems measure the total reflectance of the textured front side and the spatial angle reflectance of the back side of the wafer to ensure optimal surface treatment. Additionally, they can measure the thickness of thin layers on either the front or back of the wafer. Available in inline or offline (manual or scan) versions, they provide fast and reliable results for production and laboratory use.